It is being considered to reduce a sideways displacement of a cutting insert attached to a cutting tool, particularly an indexable cutting tool for a cut-off process and a grooving process. Japanese Unexamined Patent Publication No. 2004-223652 discloses a cutting tool configured to engage a cutting insert and a holder by a plurality of concave and convex parts. This configuration reduces the displacement of the cutting insert due to stress exerted in a sideways direction of the cutting insert.
However, as the number of the concave and convex parts is increased, it becomes more difficult to engage the cutting insert and the holder due to tolerance of size. Consequently, this type of cutting tool may suffer from poor reproducibility in the attachment of the cutting insert. For example, the cutting insert is fixed in a state of being more inclined than a desired state. Particularly, when performing a face grooving process for forming an annular groove on an end surface of a workpiece, the cutting speed on the right side of a cutting edge and the cutting speed on the left side thereof are different from each other due to a difference in machining diameter. Therefore, a twisting moment is exerted on the cutting edge part, and the cutting insert can easily be rotated. In this case, the cutting insert may cause the displacement during cutting.